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Decagon Devices, Inc.
Version: May 13, 2015 — 10:59:10
5TM
Decagon Devices, Inc.
2365 NE Hopkins Court
Pullman WA 99163
Phone: 509-332-5600
Fax: 509-332-5158
Website: www.decagon.com
Email: [email protected] or [email protected]
Trademarks
c
2007-2013
Decagon Devices, Inc.
All Rights Reserved
ii
5TM
CONTENTS
Contents
1 Introduction
1.1 Warranty . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Seller’s Liability . . . . . . . . . . . . . . . . . . . . . .
1
1
2
2 About 5TM
2.1 Specifications . . . . . . . . . . . . . . . . . . . . . . .
2.2 Background . . . . . . . . . . . . . . . . . . . . . . . .
3
3
5
3 Theory
3.1 Volumetric Water Content . . . . . . . . . . . . . . . .
3.2 Temperature . . . . . . . . . . . . . . . . . . . . . . .
6
6
6
4 Calibration
4.1 Dielectric Permittivity . . . . . . . . . . . . . . . . . .
4.2 Mineral Soil Calibration . . . . . . . . . . . . . . . . .
7
7
7
5 Connecting Sensors
9
5.1 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Communication
6.1 Serial Communication . . . . . . . . . . . . . . . . . .
6.2 Dielectric Permittivity . . . . . . . . . . . . . . . . . .
6.3 Temperature . . . . . . . . . . . . . . . . . . . . . . .
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12
12
13
7 Installing the Sensors
7.1 Procedure . . . . . . . . . . .
7.1.1 Horizontal Installation
7.1.2 Vertical Installation .
7.2 Orientation . . . . . . . . . .
7.3 Removing the Sensors . . . .
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8 Troubleshooting and Sensor Care
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8.1 Data Logger . . . . . . . . . . . . . . . . . . . . . . . . 17
8.2 Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9 Declaration of Conformity
iii
18
5TM
1
1
INTRODUCTION
Introduction
Thank you for choosing Decagon’s 5TM Soil Moisture and Temperature sensor. This manual can help you understand the sensor features
and ensure successful sensor operation. We hope you find the contents of this manual useful in understanding your instrument and
maximizing its benefit to you.
There are several ways to contact Decagon if you ever need assistance with your product, have any questions, or feedback. Decagon
has Customer Service Representatives available to speak with you
Monday through Friday, between 7am and 5pm Pacific time.
Note: If you purchased your sensor through a distributor, please contact them for assistance.
Email:
[email protected] or [email protected]
Phone:
509-332-5600
Fax:
509-332-5158
If contacting us by email or fax, please include as part of your message your instrument serial number, your name, address, phone, fax
number, and a description of your problem or question.
Please read these instructions before operating your sensor to ensure that it performs to its full potential.
1.1
Warranty
The sensor has a 30-day satisfaction guarantee and a one-year warranty on parts and labor. Your warranty automatically validates
upon receipt of the instrument.
1
1
INTRODUCTION
1.2
5TM
Seller’s Liability
Seller warrants new equipment of its own manufacture against defective workmanship and materials for a period of one year from the
date of receipt of equipment.
Note: We do not consider the results of ordinary wear and tear,
neglect, misuse, accident as defects.
The Seller’s liability for defective parts shall in no event exceed the
furnishing of replacement parts “freight on board” the factory where
originally manufactured. Material and equipment covered hereby
which is not manufactured by Seller shall be covered only by the
warranty of its manufacturer. Seller shall not be liable to Buyer for
loss, damage or injuries to persons (including death), or to property
or things of whatsoever kind (including, but not without limitation,
loss of anticipated profits), occasioned by or arising out of the installation, operation, use, misuse, nonuse, repair, or replacement of said
material and equipment, or out of the use of any method or process
for which the same may be employed. The use of this equipment constitutes Buyer’s acceptance of the terms set forth in this warranty.
There are no understandings, representations, or warranties of any
kind, express, implied, statutory or otherwise (including, but without limitation, the implied warranties of merchantability and fitness
for a particular purpose), not expressly set forth herein.
2
5TM
2
2
ABOUT 5TM
About 5TM
We designed the 5TM to measure the water content, electrical conductivity, and temperature of soil. The 5TM uses an oscillator running at 70 MHz to measure the dielectric permittivity of soil to determine the water content. A thermistor in thermal contact with the
sensor prongs provides the soil temperature. The Polyurethane coating on the 5TM circuit board protects the components from water
damage and gives the sensor a longer life span.
2.1
Specifications
Volumetric Water Content
Range: Apparent dielectric permittivity (εa ): 1 (air) to 80 (water)
Resolution: εa : 0.1 εa (unitless) from 1 to 20, < 0.75 εa (unitless)
from 20 to 80 VWC: 0.0008 m3 /m3 (0.08% VWC) from 0 to
50% VWC
Accuracy: εa : ±1 εa (unitless) from 1 to 40 (soil range), ±15% from
40 to 80 (VWC)
• Using Topp equation: ±0.03 m3 /m3 (±3% VWC) typical
in mineral soils that have solution electrical conductivity
< 10 dS/m
• Using medium specific calibration, ±0.01 to 0.02 m3 /m3 (±1
to 2% VWC) in any porous medium.
Temperature
Range: −40 to 60 ◦ C
Resolution: 0.1 ◦ C
Accuracy: ±1 ◦ C
1
Customers may use sensors at higher temperatures under some conditions,
please contact Decagon for assistance.
3
2
ABOUT 5TM
5TM
General
Dimensions: 10 cm (1) x 3.2 cm (w) x 0.7 cm (d)
Prong Length: 5.2 cm
Dielectric Measurement Frequency: 70 MHz
Measurement Time: 150 ms (milliseconds)
Power requirements: 3.6 to 15 VDC, 0.3 mA quiescent, 10 mA during 150 ms measurement
Output: RS232 (TTL) or SDI-12
Operating Temperature: −40 to 60 ◦ C1
Connector Types: 3.5 mm (stereo) plug or stripped & tinned lead
wires (Pigtail)
Cable Length: 5 m standard; Maximum 75 m.
Decagon if you need longer cable lengths.
Please contact
Data logger Compatibility (not exclusive):
• Decagon: Em50, Em50R, and Em50G
• Campbell Scientific: Any logger with serial I/O (CR10X,
CR850, 1000, 3000, etc.)
1
Customers may use sensors at higher temperatures under certain conditions,
please contact Decagon for assistance.
4
5TM
2
ABOUT 5TM
Figure 1: 5TM Components
2.2
Background
In 2006, Decagon incorporated research from its EC-5 volumetric
water content sensor into the EC-TM, a sensor that measures volumetric water content and temperature. The new 5TM uses the same
theory as the EC-TM, but has an improved calibration procedure and
SDI-12 capabilitiesthe 5TM utilizes a five point dielectric calibration
to provide more accurate dielectric permittivity measurements than
the previous EC-TM. In 2014, we changed the overmolding on the
sensor circuitry from macromelt to polyurethane to extend the life
of the sensor.
5
3
THEORY
3
3.1
5TM
Theory
Volumetric Water Content
The 5TM sensor uses an electromagnetic field to measure the dielectric permittivity of the surrounding medium. The sensor supplies a
70 MHz oscillating wave to the sensor prongs that charges according
to the dielectric of the material. The stored charge is proportional
to soil dielectric and soil volumetric water content. The 5TM microprocessor measures the charge and outputs a value of dielectric
permittivity from the sensor.
3.2
Temperature
The 5TM uses a surface-mounted thermistor to take temperature
readings. The thermistor is underneath the sensor overmold, next
to one of the prongs, and it reads the temperature of the prong surface. The 5TM outputs temperature in ◦ C unless otherwise stated
in DataTrac 3 or ECH2O Utility preferences file.
It is important to note that if the black polyurethane overmold of
the sensor is in direct sunshine, the temperature measurement may
read high. We do not recommend that the sensor be installed with
the overmold in the sun.
Note: Do not install the sensor with the overmold exposed to the
sun.
6
5TM
4
4.1
4
CALIBRATION
Calibration
Dielectric Permittivity
Decagon factory calibrates each 5TM sensor to measure dielectric
permittivity (εa ) accurately in the range of 1 (air) to 80 (water).
The unprocessed raw values reported by the 5TM in standard serial
communication have units of εa ∗ 50. When used in SDI- 12 communication mode, the unprocessed values have units of εa (for 5TM
board versions R2-04 and older, units are, εa ∗ 100).
4.2
Mineral Soil Calibration
Numerous researchers have studied the relationship between dielectric permittivity and volumetric water content (VWC) in soil. As
a result, numerous transfer equations that predict VWC from measured dielectric permittivity. You are free to use any of these various
transfer equations to convert raw dielectric permittivity data from
the 5TM into VWC. If you choose the mineral soil calibration option
in Decagon’s ProCheck reader, DataTrac 3, or ECH2O Utility, they
convert raw dielectric permittivity values with the Topp equation
(Topp et al. 1980).
VWC = 4.3 ∗ 10−6 εa 3 − 5.5 ∗ 10−4 εa 2 + 2.92 ∗ 10−2 εa − 5.3 ∗ 10−2
Our tests show that in a properly installed 5TM sensor in a normal mineral soil with saturation extract electrical conductivity < 10
dS/m, the Topp equation results in measurements within ±3% VWC
of the actual soil VWC. If you require more accurate VWC than ±3%,
are working in a soil with very high electrical conductivity, or nonnormal mineralogy, then it may be necessary to conduct a soil specific
calibration for your 5TM sensor to improve the accuracy to 1 to 2%
for any soil. For more information on how to perform your own soilspecific calibration, or to have Decagon’s calibration service perform
one for you, visit us online at http://www.decagon.com/services/soilmoisture-sensor-custom-calibration.
7
4
CALIBRATION
5TM
Calibration in Non-Soil Media
Decagon has performed calibrations with the 5TM in several nonsoil growth media. The following are suggested calibration equations
for some common materials.
Potting Soil
V W C = 2.25 ∗ 10−5 εa 3 − 2.06 ∗ 10−3 εa 2 + 7.24 ∗ 10−2 εa − 0.247
Rockwool
V W C = −1.68 ∗ 10−3 εa 2 + 6.56 ∗ 10−2 εa + 0.0266
Perlite
V W C = −1.07 ∗ 10−3 εa 2 + 5.25 ∗ 10−2 εa − 0.0685
Decagon continually develops additional calibration equations for
various other growth media as opportunities arise. Please check the
Decagon website http://www.decagon.com/pdfs/app notes/Measuri
ngWaterContentinSoil-lessMedia.pdf (case sensitive) or contact Deca
gon for the status of this ongoing research.
The 5TM can accurately read VWC in virtually any porous medium
if a custom calibration is performed. For information on how to perform your own medium-specific calibration, or to have Decagons calibration service perform one for you, visit http://www.decagon.com.
Reference
Topp, G.C., J.L. David, and A.P. Annan 1980. Electromagnetic, Determination of Soil Water Content: Measurement in Coaxial Transmission Lines. Water Resources Research 16:3. p. 574-582.
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5TM
5
5
CONNECTING SENSORS
Connecting Sensors
Decagon designed the 5TM sensor for use with our Em50 series data
loggers or the ProCheck handheld reader. The standard sensor (with
a 3.5 mm “stereo plug” connector) quickly connects to and is easily
configured within a Decagon logger or ProCheck.
The 5TM sensor incorporates several features that also make it an
excellent sensor for use with third party loggers. Customers may purchase the sensor with stripped and tinned wires (pigtail) for terminal
connections. Visit www.decagon.com/support/literature to get extensive directions on how to integrate the 5TM sensor into third
party loggers.
The 5TM sensor comes standard with a five meter cable. Customers
may purchase sensors with custom cable lengths for an additional
fee (on a per-meter fee basis). Obtaining custom length cables eliminates the need for splicing the cable (a possible failure point).
Connecting to an Em50/Em50R Logger
Decagon designed the 5TM to work specifically with the Em50 data
logger. Simply plug the 3.5 mm stereo plug connector directly into
one of the five sensor ports. Next, configure the logger port for the
5TM and set the measurement interval.
Connecting to ECH2O Utility
Please check your software version to ensure it will support the 5TM.
To update your software to the latest version, please visit Decagon’s
software download site at www.decagon.com/support/downloads.
Note: You must use the ECH2O Utility, DataTrac 3 or a terminal program on your computer to download data from the logger to
your computer.
9
5
CONNECTING SENSORS
5.1
5TM
Wiring
Figure 2: Stereo Connector
The following software support the 5TM sensor:
• ECH2O Utility 1.12 or greater
• ECH2O DataTrac 2.77 or greater
Connecting to a non-Decagon Logger
Customers may purchase 5TM sensors for use with non-Decagon data
loggers. These sensors typically come configured with stripped and
tinned (pigtail) lead wires for use with screw terminals. Refer to your
distinct logger manual for details on wiring. Our Integrator’s Guide
gives detailed instructions on connecting the 5TM sensor to nonDecagon loggers. Please visit www.decagon.com/support/literature
for the complete Integrator’s Guide.
Pigtail End Wiring
Figure 3: Pigtail End Wiring
Connect the wires to the data logger as Figure 3 shows, with the
supply wire (white) connected to the excitation, the digital out wire
10
5TM
5
CONNECTING SENSORS
(red) to a digital input, the bare ground wire to ground as illustrated
below.
Figure 4: Pigtail End Wiring to Data Logger
Note: The acceptable range of excitation voltages is from 3.6-15
VDC. If you wish to read your Decagon sensor with the Campbell
Scientific Data Loggers, you will need to power the sensors off of the
switched 12V port.
If your 5TM is equipped with the standard 3.5 mm plug and you
want to connect it to a non-Decagon data logger, you have two options. First, you can clip off the plug on the sensor cable, strip and
tin the wires, and wire it directly into the data logger. This has
the advantage of creating a direct connection with no chance of the
sensor becoming unplugged; however, it cannot be easily used in the
future with a Decagon readout unit or data logger.
The other option is to obtain an adapter cable from Decagon. The
3-wire sensor adapter cable has a connector for the sensor jack on
one end, and three wires on the other end for connection to a data
logger (this type of wire is often referred to as a “pigtail adapter”).
Both the stripped and tinned adapter cable wires have the same termination as seen above; the white wire is excitation, red is output,
and the bare wire is ground.
11
6
COMMUNICATION
6
5TM
Communication
The 5TM sensor communicates using two different methods, Serial
(TTL) and SDI-12. Please visit www.decagon.com/support/literature
for the complete Integrator’s Guide, which gives more detailed explanations and instructions.
6.1
Serial Communication
When excitation voltage is applied, the 5TM makes a measurment.
Within about 120 ms of excitation three measurement values are
transmitted to the data logger as a serial stream of ASCII characters. The serial out is 1200 baud asynchronous with 8 data bits, no
parity, and one stop bit. The voltage levels are 0-3.6V and the logic
levels are TTL (active low). The power must be removed and reapplied for a new set of values to be transmitted.
The ASCII stream contains 3 numbers separated by spaces. The
stream is terminated with the carriage return character. The first
number is raw dielectric output. The second number is 0 (ignore
this value) and the third number is raw temperature. The following
explains how to convert the raw values into their standard units.
6.2
Dielectric Permittivity
The raw dielectric value (εRaw ), is valid in the range 0 to 4094. This
corresponds to dielectric permittivity values 0.00 to 81.88. The 5TM
uses the εRaw value of 4095 to indicate the dielectric permittivity
portion of the sensor is not working as expected.
The εRaw value is converted to dielectric permittivity with the following equation:
Dielectric Permittivity =εa = εRaw / 50
12
5TM
6.3
6
COMMUNICATION
Temperature
The raw temperature value, (TRaw ), is valid in the range 0 to 1022.
The 5TM uses a compression algorithm to extend the range of temperatures that can be represented by a 10-bit value. The sensor sends
temperature with 0.1 of a degree Celsius resolution for the range −40
to 50.0 ◦ C. For the range 50.5 to 111.0 the sensor sends temperature
with a 0.5 of a degree resolution. Temperatures outside this range
are truncated to the maximum or minimum values as appropriate.
The 5TM uses the TRaw value of 1023 to indicate the temperature
portion of the sensor is not working as expected.
If TRaw ≤ 900 then TRaw2 = TRaw
If TRaw > 900 then TRaw2 = 900 + 5 (TRaw - 900)
Temperature(◦ C)=(TRaw2 - 400)/10
The 5TM sensor also communicates using SDI-12 protocol, a threewire interface where all sensors are powered (white wire), grounded
(bare wire), and communicate (red wire) on shared wires (for more
info, go to www.sdi-12.org). If you plan on using SDI-12 for communication with the 5TM, please see our Integrator’s Guide at www.deca
gon.com/support/literature for detailed instructions.
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7
INSTALLING THE SENSORS
7
5TM
Installing the Sensors
Decagon has a few helpful reminders to consider before beginning to
use your sensor.
• If you are installing sensors in a lightning prone area with
a grounded data logger, please see our Application Note at
www.decagon.com/sensorappnotes.
• Decagon advises that you test the sensors with your data logging device and software before going to the field.
Before you select a site for installation, remember that the soil next
to the sensor surface has the strongest influence on its readings. It
is important to avoid air gaps or extremely compact soil around the
sensor, which can skew readings. Do not install the 5TM next to
large metal objects, which can attenuate the sensor electromagnetic
field and distort output readings.
Because the sensors have gaps between their prongs, it is also important to consider the size of the media where you insert the sensor. It
is possible to get sticks, bark, roots or other material stuck between
the sensor prongs, which will adversely affect readings. Finally, be
careful when inserting the sensors into dense soil, as the prongs can
break if you apply excessive force when pushing them into the soil.
7.1
Procedure
Customers can insert the 5TM directly into growing media or soil.
We have sharpened the tip of each prong to make it easier to push the
sensor into the soil. Remember to be careful around the sharpened
tips. The sensor needs to be completely covered by soil, as shown in
Figure 5.
14
5TM
7
INSTALLING THE SENSORS
Figure 5: 5TM Proper Installation
The sensors may be difficult to insert into extremely compact or dry
soil. If you have difficulty inserting the sensor, try loosening the soil
somewhat or wetting the soil. Never pound the sensor into the soil,
as you could damage the instrument.
7.1.1
Horizontal Installation
Excavate a hole or trench a few centimeters deeper than the depth at
which the sensor is to be installed. At the installation depth, shave
off some soil from the vertical soil face exposing undisturbed soil.
Insert the sensor into the undisturbed soil face until the entire sensing
portion of the sensor. The tip of each prong has been sharpened to
make it easier to push in the sensor. Be careful to avoid the sharp
tips. Backfill the trench taking care to pack the soil back to natural
bulk density around the black polyurethane portion of the sensor.
7.1.2
Vertical Installation
Auger a 4-inch hole to the sensor installation depth. Insert the sensor into the undisturbed soil at the bottom of the auger hole using
your hand or another implement to guide the sensor into the soil at
the bottom of the hole. Many people have used a simple piece of
PVC pipe with a notch cut in the end for the sensor to sit in, with
15
7
INSTALLING THE SENSORS
5TM
the sensor cable routed inside the pipe. After inserting the sensor,
remove the installation device and backfill the hole taking care to
pack the soil back to natural bulk density while not damaging the
black plastic portion of the sensor or the sensor cable in the process.
7.2
Orientation
Users can orient Decagon sensors in any direction. Because the sensors have prongs instead of a blade (like the EC-10 and EC-20), you
can place them in any orientation that meets your requirements.
7.3
Removing the Sensors
When removing the 5TM sensor, do not pull it by the cable. This
could break the internal wires and cause the sensor to malfunction
or not function at all.
16
5TM
8
8
TROUBLESHOOTING AND SENSOR CARE
Troubleshooting and Sensor Care
Before contacting Decagon about sensor malfunctions, follow the
data logger and sensors troubleshooting steps 1 through 3.
8.1
Data Logger
1. Check to make sure the connections to the data logger are both
correct and secure.
2. Ensure that your data logger batteries are not dead or weakened.
3. Check the configuration of your data logger in ECH2O Utility
or ECH2O DataTrac to make sure you have selected 5TM.
8.2
Sensors
1. Ensure that your sensors are installed according to the “Installation” section of this manual.
2. Check sensor cables for nicks or cuts that could cause a malfunction.
17
9
DECLARATION OF CONFORMITY
9
5TM
Declaration of Conformity
Application of Council Directive:
2004/108/EC and 2011/65/EU
Standards to which conformity is
declared:
EN 61326-1:2013 and
EN 50581:2012
Manufacturer’s Name:
Decagon Devices, Inc. 2365 NE
Hopkins Ct. Pullman, WA 99163
USA
Type of Equipment:
Dielectric Soil Moisture Sensor
Model Number:
ECH2O-TE/EC-TM/5TM/5TM
Year of First Manufacture:
2005
This is to certify that the ECH2O-TE, EC-TM, 5TE, and 5TM
dielectric soil moisture sensors, manufactured by Decagon Devices,
Inc., a corporation based in Pullman, Washington, USA meets or exceeds the standards for CE compliance as per the Council Directives
noted above. All instruments are built at the factory at Decagon and
pertinent testing documentation is freely available for verification.
18
Index
CE Compliance, 18
Communication, 12
Connecting
ECH2O Utility, 9
Em50 Series Data Logger, 9
Contact Information, 1
Specifications, 3
Temperature, 6
How 5TM Measures, 6
Troubleshooting, 17
Vertical Installation, 15
Volumetric Water Content, 3
Declaration of Conformity, 18
Dielectric Permittivity, 7
Warranty, 1
Wiring
Pigtail, 10
Stereo Plug, 10
ECH2O Utility, 10
Email, 1
Horizontal Installation, 15
How the TE Works
Temperature, 6
Volumetric Water Content, 6
Installation
Orientation, 16
Removing the Sensor, 16
Integrator’s Guide, 10, 12
Logger
Communications, 11
Non-Decagon, 10
Mineral Soil Calibration, 7
Power Requirements, 4
Seller’s Liability, 2
Sensor
Accuracy, 3
Components, 5
Installation, 14
Range, 3
Resolution, 3
19